Crane Load Calculator

1. Identify your crane model and configuration. Load charts are specific to boom length, counterweight, and outrigger setup.
2. Find your working radius. This is the horizontal distance from crane center to hook. The load chart rows show radius values.
3. Read across to your boom length. The intersection gives rated capacity in tonnes or pounds.
4. Check for deductions. Subtract weight of hook block, slings, and rigging hardware from rated capacity.
5. Verify boom angle. Some charts list angle instead of radius. Never exceed the chart's minimum angle for your radius.
6. Account for wind and dynamic effects. Load charts assume static conditions. High winds or sudden stops reduce effective capacity.

Load Moment = Load Weight × Working Radius (t·m). It represents the overturning force trying to tip the crane forward.

Working Radius = Horizontal distance from crane centerline to the hook. As radius increases, load moment increases, and safe capacity must decrease.

Think of it like a seesaw: the further the load sits from the pivot (crane center), the more it tries to tip the crane. The crane's counterweight and base width resist this tipping moment.